1. Technical Field
The present disclosure relates to magnetic resonance imaging (MRI) and, more specifically, to an efficient estimator of pharmacokinetic parameters in breast MRI.
2. Discussion of Related Art
Magnetic resonance imaging (MRI) is a medical imaging technique in which a human subject can be imaged in three-dimensions with a great deal of detail pertaining to the differentiation of different forms of bodily soft tissue. Thus MRI is well suited for the visualization and diagnosis of the human breast. In MRI, the human subject is exposed to a powerful magnetic field which aligns the nuclear magnetization of hydrogen atoms in water within bodily tissues. Radiofrequency fields are used to systematically alter the alignment of this magnetization and the hydrogen nuclei then produce a rotating magnetic field detectable by the scanner.
Structural image data may be generated from the received data signals to construct an image of the body. For example, the structural image may be generated from a number of spatial frequencies at different orientations. Frequency and phase encoding are used to measure the amplitudes of a range of spatial frequencies within the object being imaged. The number of phase-encoding steps performed may be selected to determine how much imaging data may be collected.
As MRI uses magnetic and radiofrequency fields to perform visualization, the patient is not exposed to potentially hazardous ionizing radiation as would be the case with CT scans.
While the MRI may be used to differentiate between various types of soft tissue, it may be difficult to precisely differentiate between benign and malignant lesions that are found within the human breast.
A magnetic contrast agent, such as one based on chelates of gadolinium may be administered to the patient subject prior to the acquisition of the MRI. As the contrast agent may be easily observed from the MRI, injecting the magnetic contrast agent into the blood stream of the patient subject may be highly useful in visualizing the way in which chemicals placed into the blood are absorbed and washed out of various types of tissue. Such an investigation is known as pharmacokinetics as it relates to the study of the nature of movement of chemical substances through the bodily tissue. The process of analyzing the pharmacokinetics of the contrast agent by MRI is known as dynamic contrast-enhanced (DCE) MRI.
In particular, in performing DCE MRI, a first MR image may be acquired prior to the administration of the magnetic contrast agent and then subsequent MR images may be acquired at regular intervals as the contrast agent is absorbed and washed out of the tissue under Investigation. The sequence of MR images may then be analyzed to profile the nature of the absorption and washout. It is known that benign and malignant lesions within the breast may exhibit distinct pharmacokinetic profiles and thus this analysis may be highly useful in identifying one or more regions of interest that are breast malignancy candidates. After the one or more candidates have been identified, advanced pharmacokinetics (PK) analysis may be performed on the DCE MRI image data to quantitatively describe the absorption and washout of the contrast agent (CA) into and out from the candidate regions of interest for the purposes of differentiating between malignant and benign lesions.
While existing approaches to PK analysis in DCE MRI may provide some level of characterizing candidate regions of interest, this data tends to be difficult to normalize, and as such, it may be exceedingly difficult to compare the PK analysis data across data sets from one or more patients and/or between various MR systems. This difficulty in performing such comparisons impairs the effectiveness of research such as population studies.